Torque Wrench
#11
RE: Torque Wrench
I used to only have a Craftsman 1/2 drive that goes to something like 250 ft/lbs, but then I added a Craftsman that does inch/lbs as well.
I actually have some follow on questions about torque wrenches and their us:
Which is better, a dial indicator type, or the click type. I have read that the click types are the worst to have for accuracy.
Also, in situations where you can get a wrench on either, is there a difference in taking your torque reading off of the nut, or the bolt or does it not matter?
Lastly, is a torque wrench still acurate if you have long extensions on it? I have had to torque bolts that I could only reach using a 4" and 8" extension hooked together, and then a deep socket on the end. This always feels like it makes tightening more difficult due to the instability of the long reach. Is this affecting the torque reading too?
Thanks.
I actually have some follow on questions about torque wrenches and their us:
Which is better, a dial indicator type, or the click type. I have read that the click types are the worst to have for accuracy.
Also, in situations where you can get a wrench on either, is there a difference in taking your torque reading off of the nut, or the bolt or does it not matter?
Lastly, is a torque wrench still acurate if you have long extensions on it? I have had to torque bolts that I could only reach using a 4" and 8" extension hooked together, and then a deep socket on the end. This always feels like it makes tightening more difficult due to the instability of the long reach. Is this affecting the torque reading too?
Thanks.
#12
RE: Torque Wrench
When you have extensions on a torque wrench,
they add the 'springy' twist you describe.
The fancy engineer's word for 'springy' is 'elastic deformation'.
If you keep applying force to the wrench with the extensions until the handle comes to a stop,
then the torque value you read is accurate.
But if you read the torque value while the wrench handle is still moving you will read low.
Click, dial, or digital readout torque wrenches are all ok as long as you check the calibration.
If you live anywhere new Oak Ridge National Laboratory outside Knoxville TN,
go there on 'Visitors Day' and get your torque wrench checked free at the instrument laboratory.
I would guess Los Alamos, Scandia, Livermore, and Battelle labs have similar visitor days.
Otherwise you can send your torque wrench to companies like SnapOn and Mac and they will calibrate them for a fee. Sometimes the SnapOn or Mac tool vans carry torque calibrators.
Or get the correct 8 point socket that will go over 3/8ths, half inch or 3/4 square drives and test a new torque wrench at Sears or Home Depot against your old one.
they add the 'springy' twist you describe.
The fancy engineer's word for 'springy' is 'elastic deformation'.
If you keep applying force to the wrench with the extensions until the handle comes to a stop,
then the torque value you read is accurate.
But if you read the torque value while the wrench handle is still moving you will read low.
Click, dial, or digital readout torque wrenches are all ok as long as you check the calibration.
If you live anywhere new Oak Ridge National Laboratory outside Knoxville TN,
go there on 'Visitors Day' and get your torque wrench checked free at the instrument laboratory.
I would guess Los Alamos, Scandia, Livermore, and Battelle labs have similar visitor days.
Otherwise you can send your torque wrench to companies like SnapOn and Mac and they will calibrate them for a fee. Sometimes the SnapOn or Mac tool vans carry torque calibrators.
Or get the correct 8 point socket that will go over 3/8ths, half inch or 3/4 square drives and test a new torque wrench at Sears or Home Depot against your old one.
#13
RE: Torque Wrench
ORIGINAL: HankL
Kolkut you do not understand what torque is,
if you think putting the scale at 4 foot and pulling it to 25 lbs is the same as pulling 25 lb at one foot.
At four feet it is 100 ft-lbs. (25 x 4)
At one foot it is 25 ft-lbss. (25 x 1)
The first time I used a fish scale to torque a nut
it was with a 10 foot extension to put 500 ft-lbs on the flange bolts of a 20 inch by 20 inch centrifugal pump driven by a 1200 horsepower electric motor.
Kolkut you do not understand what torque is,
if you think putting the scale at 4 foot and pulling it to 25 lbs is the same as pulling 25 lb at one foot.
At four feet it is 100 ft-lbs. (25 x 4)
At one foot it is 25 ft-lbss. (25 x 1)
The first time I used a fish scale to torque a nut
it was with a 10 foot extension to put 500 ft-lbs on the flange bolts of a 20 inch by 20 inch centrifugal pump driven by a 1200 horsepower electric motor.